Create your own Dual Sided disks

[vitualis]

For now, I have to assume the data layer of a DVD is centered in the polycarbonate, with a shorter focal length than a CD. And, correct me if I'm wrong, but aren't DVD ROMs dual lasered to be able to read both media?

The data layer of a single layered single sided DVD is pretty much similar to a CD -- very close to the top.

The data layer of a single layered dual sided DVD will have both data layers near the centre of the disc (in terms of its width).

For dual layered discs, the second data layer is about halfway between the first one and the "bottom" surface of the disc.

Regards.

[BJ_M]

except on a cd it IS the top and on a dvd is it under some plastic ..












[[/code]

[Bob W]

I have noticed that the thickness of DVDR media varies with different manufactures. The cheap media seems to be thicker.

[txpharoah]

@dcsos :P
That's great. Sad that it happened. But funny to look at. Did that once too.

@most people here... good responses to an otherwise uneducated question

@people thinking you can glue discs together... WTF were you thinking? Maybe if I add more wheel to my car (by gluing them onto the doors) it'll go faster! Seriously. Do some research. There are dozens of white papers on the topics at both the DVD forum sites and the disc manufacturer sites giving out most of this info.

Ah well... I really enjoyed this one...

[vitualis]

except on a cd it IS the top and on a dvd is it under some plastic ..

Cool pictures...

Regards.

[BJ_M]

they were on the http://www.usbyte.com web site but ive seen the same ones on other sites so i dont know where they are from at first ..

[gmatov]

Tex,
I do believe this thread started as a gag.
Everybody got too damn serious about their pet theories to keep in a light vein.
I got on focal length., Vitualis insisted the data layer of a DVD was the same as a CD, adjacent to the lable, Vitualis posted schematics of the actual design of 4 formats, people show actual examples of tear offs. Boy, if a torn off lable takes the media apart, I can only say they must have been designed for the media companies. Try to remove OUR lable and it's toast!!
They ARE fragile, aren't they?

George
I tried to upload a pic of my latest g'son, 4 days old now, and can't do it. Why not? I followed the dirs below, I think.

[vitualis]

Well, I think that the original poster was serious (and BTW, the pasting of two discs together to make a "double-sided" disc has been discussed on this forum several times before...)

My original post was in response to "why we don't see double sided CDs"... Down the thread, several people were confusing DVDs for CDs or dual-layered DVDs for double-sided DVDs...

As for tearing off a label off a CD, I don't believe there is really any question about what happens is there? This is an issue on how CDs are designed rather than dodgey media. Get one of the free AOL CDs (that pressed disc) and scratch a key on the top surface. Now look at the bottom... Dead CD.

Regards.

[gmatov]

Michasel,
I'd like to say, I refuse to believe, except that thru these pages, and other forums, fora, forii (?), some one will always come up with some thing, let's say, out of the ordinary?
I don't think the original posted a serious comment. I think it was a gag. It's also 6 or 7 months old, and someone found it and re-opened it, and, like a bunch of suckers, we all jumped on why it wouldn't work, or would be impractical, or whatever.
I think we're all goofy, in our own way. Some are just a tad further over the line, perhaps?

[vitualis]

8)

Regards.

[VinnySem]

Yanno... I bet if you glue two disks together, then install two identical DVD burners one on top of the other, with the top one upside down, you could burn both sides simultaneously!

I also hypothesize that would work with set top players!!!
Wooohoooooo!!!!!!

[w00tski]

LOL




seriously this post bought a tear to my eye

[gmatov]

We finally hit 8X

[VinnySem]

We finally hit 8X

where do you see 8X?

[gmatov]

Vinny,
With your "dual sided" and the two burners together. You'd use 4X wouldn't you? 4+ 4 = 8

[handyguy]

Meritline.com has Ritek PrimeDisc DVD-R 9.4GB Double-Sided Media, lowest as $3.10 each

[Gil T Pleasure]

The only way of making a dual sided CD-R that is IN SPEC would be to somehow change the refractive index of the polycarbonate substrate so that a 0.6mm layer would appear to the reading laser as 1.2mm. This is probably not a trivial thing to accomplish and as yet, no one has made a commercial product that does such a thing.

The so called "dual disc" does such a thing. It combines a CD on one side and a DVD on the other.

How is this different from SACD?

[gmatov]

Gil,

Now, I don't believe that for a moment.

All disks are the same .048 in thickness. A CD laser focuses at that distance for CD, half that, .024, for DVD.

IF you made the disk to be .072+ ( if you could have both reflective layers back to back, + because you would have to have a thou or 2 between them) the laser would have to "see" through one reflective layer to "burn" the other..

The lasers do focus from the bottom, so the variation in thickness in some brands don't kill too many disks

[Gil T Pleasure]

gmatov,

I think you misunderstood me. When I said "dual disc" I didn't mean dual layer disc that Philips just announced (ie, DVD+R9). I meant the dual disc created by Sony.

Under the proposal, a single disc would combine a music album on one side and a digital versatile disc (DVD) on the other.

See: http://www.cdr-info.com/Sections/News/Details.asp?RelatedID=4133

[Cornucopia]

I know that there have be mixed/dual format discs around for a little while now. As much as 6 mo. ago, I saw a copy of "Blair Witch 2" at the used/discount DVD rack at my local County Market grocery store. It was touted as a "DVDPlus", and has DVD on 1 side and CD on the other. I was curious, but wouldn't pay the $10.00US. I don't like BW2 that much!

Scott

[robb7979]

I did it everyone!!
I super glued 4 dvd-r's together. Now I just gotta test it out with all of my players/burners. I'll let you all know!-rob

[SaSi]

Long thread. And nice pics.

The picture of the removed label reminded me of a CD I left on top of my monitor that got the silver label peeled-off by the heat. It was funny - not my disk or my data on it.

Actually, there is a very good reason to stick two disks back-to-back. I get an MSDN universal subscription on CDs and I also get some very interesting but useless language versions like Russian, Brazilian Portugeeze, etc. I glued many of them back-to-back and made some hi-tech coasters for my coffee class.

I just put one of them in the DVD-ROM (complete with scratches and stuff) and guess what? It worked.

[Gil T Pleasure]

How is this different from SACD?

SACD is dual layer disc (first layer is CD, second layer is SACD) whereas the dual disc is a flipper (CD on one side, DVD on the other).

Good info with pretty picture here:
http://www.disctronics.co.uk/technology/dvdintro/dvd_hybrid.htm